/Engine/Source/Runtime/CoreOnline/Public/Online/CoreOnline.h
Register a registry for a given OnlineServices implementation and IOnlineSessionIdHandle type
void RegisterSessionIdRegistry ( [EOnlineServices](API\Runtime\CoreOnline\Online\UE__Online__EOnlineServices) OnlineServices, [IOnlineSessionIdRegistry](API\Runtime\CoreOnline\Online\IOnlineSessionIdRegistry) * Registry, int32 Priority )